[3.1.0] Fix and revamp configForm.php smoketest

- Fix bool/null ConfigForm field

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1694 48356398-32a2-884e-a903-53898d9a118a

configdoc/generate.php

@@ -38,6 +38,7 @@ $configdoc_xml = 'configdoc.xml';
 $xml_builder = new HTMLPurifier_ConfigSchema_Builder_Xml();
 $xml_builder->openURI($configdoc_xml);
 $xml_builder->build($interchange);
+unset($xml_builder); // free handle
 
 $xslt = new ConfigDoc_HTMLXSLTProcessor();
 $xslt->importStylesheet(dirname(__FILE__) . "/styles/$style.xsl");